Is it possible to boot Vista from vhd using Windows 7 boot manager?

I have a live Vista system which I want to upgrade to Windows 7. However, I don't want to break everything and ideally want to be able to rollback if Windows 7 would take longer time to configure (i need to continue with my projects, i cant just spend days troubleshooting the process).

At the moment I have W7 installed and running from vhd. My next step is to copy current working Vista into vhd file using disk2vhd utility so that then i can run it form Windows 7 if it would take longer time to configure W7 properly.

Then I will install W7 on the partition where Vista is at the moment erasing it (custom install as i move from 32 bit to 64 bit). Basically i want to swap them around - to have W7 on C: instead of vhd and move Vista from C:\ to vhd.

So, my question is once I have Windows 7 boot manager (well, it is already there) would i be able to boot into Vista installed on vhd? It may work if actual boot manager does mounting of vhd before OS begin to load. Or is it actually feature of W7 itself, not just boot manager?

Note, i dont want to create another partition and install W7 there. Yes, it would guarantee i have my Vista live and running, but it is too messy.

It wont work. I have tried adding it same way i added virtual Windows 7 to Windows 7 boot manager:

bcdedit /copy {default} /d "Windows Vista"
bcdedit /set {My_new_GUID_Number} device vhd=[C:]\vista.vhd 
bcdedit /set {My_new_GUID_Number} osdevice vhd=[C:]\vista.vhd 

So, when i selected Windows Vista from boot menu first it ran Windows 7 repair to fix windows installation and then after restart boot manager was screwed - no OS would boot. It was back to normal after i deleted Vista entry from boot manager.